1. Field of the Invention
The present invention relates to a vehicle motion controlling apparatus which cooperatively performs a steering control and a braking control for a vehicle to control the motion of the vehicle.
2. Description of Related Art
A vehicle has a steering angle control mechanism and a torque control mechanism. The steering angle control mechanism automatically controls the steering angle of front wheels independently of a driver's steering operation. The torque control mechanism automatically controls the transmission of a torque, generated in an internal combustion engine, to rear wheels through gears and a clutch disc. Published Japanese Patent First Publication No. 2008-94214 discloses a vehicle motion controlling apparatus for appropriately distributing controlled variables to these mechanisms. This apparatus decides these controlled variables to provide a vehicle motion matching to a normative yaw rate. This decision is automatically performed such that loads applied to the wheels are appropriately set when the vehicle is accelerated.
However, when the vehicle is, for example, turned while being decelerated, the apparatus cannot appropriately distribute controlled variables to the mechanisms. For example, when a driver of the vehicle having the apparatus finds out an object such as another vehicle suddenly driving out in front of the vehicle, the driver manually performs a turning operation and a deceleration operation to urgently avoid the object. Further, when the vehicle running on a downward path or running at a high speed goes into a corner of a road, the driver needs the apparatus automatically assisting the driver in decelerating the vehicle to turn the vehicle while decelerating the vehicle. In these cases, the mechanisms of the apparatus independently perform the steering control and the braking control for the vehicle. For example, only the steering angle control mechanism automatically performs the steering control at the urgently object avoiding time to turn the vehicle, or only the torque control mechanism automatically performs the braking control at the deceleration assisting time to decelerate the vehicle.
When the apparatus controls the vehicle motion by automatically performing only the steering control or only the braking control to urgently avoid the object or to assist the driver in decelerating the vehicle, it is required of the driver to manually operate a brake pedal or a steering wheel of the vehicle at a large manipulated variable. Therefore, a burden on the driver in driving the vehicle becomes large.